Interpretive Summary: To study the ability of antioxidant diets to prevent the adverse effects of iron radiation on behavior, rats were maintained on diets containing either 2% blueberry or strawberry extract or a control diet for 8 weeks prior to being exposed to iron radiation. Three days following irradiation, the rats were tested for the effects of irradiation on the acquisition of an amphetamine- or lithium chloride-induced (LiCl) conditioned taste avoidance (CTA). The CTA paradigm measures the avoidance by rats of a sucrose solution that has been paired with a high dose of a drug, such as amphetamine. The LiCl is used as a control. The irradiated rats maintained on the control diet failed to show the acquisition of a CTA following injection of amphetamine, which is similar to what we have seen in previous radiation experiments. In contrast, the rats maintained on antioxidant diets (strawberry or blueberry extract) continued to show the development of an amphetamine-induced CTA following exposure to iron radiation. As expected, since it was included as a control, all rats regardless of radiation or diet group showed acquisition of a LiCl-induced CTA. Therefore, oxidative stress following exposure to iron radiation may be responsible for the disruption of amphetamine-induced CTA in rats fed control diets, and it appears that the antioxidant diets reduce this oxidative stress to reinstate the CTA. The failure of either irradiation or diet to influence LiCl-induced responding suggests that oxidative stress may not be involved in CTA learning following injection of LiCl. The results show that exposure to radiation can produce long-term changes in behavioral functioning that can be alleviated by antioxidant diets.

Technical Abstract:
Rats were maintained on diets containing either 2% blueberry or strawberry extract or a control diet for 8 weeks prior to being exposed to 1.5 Gy of 56Fe particles in the Alternating Gradient Synchrotron at Brookhaven National Laboratory. Three days following irradiation, the rats were tested for the effects of irradiation on the acquisition of an amphetamine- or lithium chloride-induced (LiCl) conditioned taste avoidance (CTA). The rats maintained on the control diet failed to show the acquisition of a CTA following injection of amphetamine. In contrast, the rats maintained on antioxidant diets (strawberry or blueberry extract) continued to show the development of an amphetamine-induced CTA following exposure to 56Fe particles. Neither irradiation nor diet had an effect on the acquisition of a LiCl-induced CTA. The results are interpreted as indicating that oxidative stress following exposure to 56Fe particles may be responsible for the disruption of the dopamine mediated amphetamine-induced CTA in rats fed control diets; and that a reduction in oxidative stress produced by the antioxidant diets functions to reinstate the dopamine-mediated CTA. The failure of either irradiation or diet to influence LiCl-induced responding suggests that oxidative stress may not be involved in CTA learning following injection of LiCl.